This invention relates to cutting or severing thin amorphous metal material and especially to a method which does not result in the production of burr on the cut edge.
Amorphous metals present an attractive opportunity to substantially reduce magnetic losses in electrical machinery and transformers. The losses in these magnetic materials are at least a factor of 10 lower than those normally encountered in the best magnetic steels. Unfortunately, the physics of the amorphous metal forming process requires that thicknesses of the material be no more than one and one-half or two mils in total. This is in contrast to normal electrical sheet thicknesses which are on the order of 20 mils in thickness. Consequently, if conventional technology were employed to form punchings from amorphous metal sheet, there would be a ten to twenty fold increase in the number of punchings which have to be produced, and furthermore since the material thicknesses is reduced by the same factor, die clearances and precision of punch presses would have to be improved accordingly. While the technical feasibility of punching materials of that thickness is being evaluated, even if successful, this process is likely to be tedious and expensive.
It is possible to cut completely through amorphous metals using laser beams or electron beams, but if this is done the cutting rate is unacceptably slow and molten or vaporized material adjacent to the cut edge tends to run or recondense, forming burrs which prevent compact stacking of the resulting cut laminations. Stator slot cutting of amorphous metal tape by a laser beam is disclosed in U.S. Pat. No. 4,187,441 to W. R. Oney. A process for fabricating shaped laminations directly from the liquid alloy melt is covered by U.S. Pat. No. 4,155,397 to V. B. Honsinger and R. E. Tompkins. Both are assigned to the instant assignee.